Method for inserting weft threads and thread feed device

ABSTRACT

The invention relates to a method for inserting weft yarn material, comprising an insertion system in a loom. According to the invention, for every insertion the insertion system (A) is supplied with a substantial part of the weft yarn required for the insertion in a loose and substantially tension-free manner so as to be intermittently pulled off. A tubular package of adjacent windings is produced from the weft yarn material on an inner mechanical support (S) by way of an at least substantially continuous winding process and is conveyed forward in withdrawal direction. For an insertion, a number of windings that corresponds at least approximately to the weft yarn section intended to be inserted is detached or set free from the support while maintaining its tubular configuration without yarn tension. The weft yarn material is withdrawn directly inwardly from the frontmost winding and then further along the tube axis (X).

[0001] The invention relates to a method according to the preamble ofclaim 1, to a yarn feeding device according to the preamble of claim 14,and to yarn feeding device according to the preamble of claim 52.

[0002] According to known methods a winding package consisting ofcontacting or separated and spaced apart windings is formed on a storagebody. The insertion system pulls the yarn from the winding package overthe front end of the storage body. The windings on the storage body maybe advanced forward by different advance assemblies. The storage body isaxially longer than the winding package. During withdrawal a yarnballoon is formed which generates significant yarn tension variationsand a considerable yarn tension which both delay the insertion. In orderto achieve high insertion speeds a considerable energy input thus isneeded in the insertion system. On the other hand this means a highmechanical load for the weft yarn. The most important drawback is thelong insertion time dictated by this method, i.e. the time periodbetween the start of the insertion and the arrival of the then stoppedweft yarn at the opposite fabric edge. The basically very highefficiency potential of modern weaving machines cannot be usedsatisfactorily due to the long insertion time of such known insertionmethods. Furthermore, other methods are known according to which theinsertion system does not directly withdraw the weft yarn from thewinding package on a storage body but instead weft yarn material ispresented for the insertion system in loose and substantiallytensionless condition. The influence of a yarn balloon is avoidedthereby such that higher insertion speeds can be achieved with lowenergy input while the weft yarn material is treated with respect. Forexample, a weft yarn portion is presented by mechanical means in zigzagform or loop form. The mechanical means release the weft yarn portion insynchronism with the withdrawal motion. The method needs high efforts interms of the devices but is too slow for modern weaving machines becauseof the mass inertia of the mechanical elements and a plurality of veryprecisely controlled movements of the mechanical elements.

[0003] There are further methods according to which the weft yarn ispresented by mechanical means in a single large loop to the insertionsystem. The loop is released with the start of the insertion. In thiscase an undesirably large space is needed and the achievable insertionspeeds are limited.

[0004] Finally, it is known to present the weft yarn section to theinsertion system loosely and substantially without tension in randomconfiguration in the interior of a cavity. The random configuration ofthe weft yarn section easily might lead to disturbances due to weft yarnbreakages and yarn tension variations during the withdrawal.

[0005] It is an object of the invention to provide a method and a yarnfeeding device, as mentioned above, which allow to achieve optimal shortinsertion times with low energy consumption and high operational safetyin highly efficient modern weaving machines.

[0006] Said object is achieved by the features of claim 1, the featuresof claim 14 and the features of claim 52.

[0007] Surprisingly, the winding package portion set free from thesupport for the withdrawal in orderly arranged windings shows atendency, among others, due to the inherent inertia property and theform stability of the windings, to safely remain in a tubularconfiguration in the free space even without any mechanical innersuspension and such that the weft yarn during withdrawal first runsinwardly from the tube without forming any balloon and then runs furthercentrally and consumes the windings from the tube in a clean fashion,even up to the last in-fed winding which may still be supported on thesupport. The released winding package section does not collide. Thewindings do not tend to entangle or to collapse, provided that thewithdrawal is carried out rapidly and in a timewise precisely controlledadaptation to the release of the winding package section. Astonishinglyshort insertion times can be achieved by the method. The astonishinglyshort insertion times allow to optimally use the capabilities of modernweaving machines in terms of high yarn speeds and high insertionfrequencies. The released yarn package section may be supported from theouter side. Such a suspension, however, is more a safety measure.Expediently, the winding on speed of the substantially continuouswinding process may be matched with the insertion frequency and thelength of the respective inserted weft yarn section such that eachinsertion substantially consumes the released winding package sectionbefore a subsequent winding package section is released. Even in case ofextremely high yarn speeds it can be seen that the centrally withdrawnweft yarn does consume the first winding in withdrawal directionsubstantially radially inwardly and without any ballooning and that thetubular configuration of the windings in the released winding packagesection is maintained till the end of the insertion with optimum yarngeometry. The released winding package section may contain a number ofyarn windings which substantially correspond to the weft yarn lengthwhich is to be inserted, or may contain a larger number corresponding toseveral weft yarns which are to be inserted one after the other.

[0008] It may be expedient to overlap the withdrawal timewise with therelease of the winding package section such that the released windingpackage section or the windings at the withdrawal side of the windingpackage section, respectively, have as little time as possible to leavethe tubular configuration of the orderly arranged windings.

[0009] The method can be carried out in a simple way if the windings inthe winding package section are set free by axial overfilling of theinner support beyond the withdrawal side end of the support. Thereleased windings are consumed during the withdrawal before the releasedwinding package section can collide or get into a state of disorder. Theoverfilling is carried out by continuous winding on of new weft yarnmaterial.

[0010] Alternatively or additively the windings may be released byadvancing the winding package on the support beyond the withdrawal sideend of the support. In this case advance assemblies of any suitable kindmay be employed.

[0011] In order to maintain the tubular configuration of the releasedyarn package section as stably as possible, and in order to optionallyeven use the natural adhesion between the contacting windings, thewinding package and the released winding package section may be conveyedin withdrawal direction obliquely upwards.

[0012] A further alternative may be to release the windings in thewinding package section released for withdrawal by a respectiveconveying movement or adjusting movement of at least a part of thesupport. In this case mechanical adjusting devices of the support may beemployed.

[0013] It is important for the course of the method to extend thetendency of the released winding package section to remain freely inspace without inner mechanical suspension as long as possible. Thistendency also depends on the form stability of the yarn material and thewindings and from the at least preliminarily inherent form stability ofthe winding package section. The form stability is good when thewindings are wound on the support with a curvature of the yarn materialwhich at least substantially corresponds to the smallest natural andunforced capability of the weft yarn material to store a curvature. Saidcapability to store the curvature may be explained as follows: a sectionof the weft yarn material is laid on a smooth surface. Both ends of thesection are brought towards each other as close as possible. By this theweft yarn section receives a certain curvature. If then both ends arereleased, the weft yarn section will relax into a residual curvaturerepresenting the smallest natural capability to store a curvature.Surprisingly, it has been found that different weft yarn materialsbehave only slightly differently or behave even very similarly. In casethat the weft yarn material in the winding package is wound at leastsubstantially with the smallest natural capability to store a curvature,then the windings in the released winding package section will not havea considerable tendency to increase or decrease the winding radiusthemselves such that the released winding package section maintains thetubular configuration formed by the winding process on the inner supportrelatively long even if there is no further support from inside. Anyadhesion between the equally formed contacting windings can support thiseffect.

[0014] In case of insertion methods employing an insertion system whichitself cannot precisely measure the length of the respective insertedweft yarn section it may be expedient to mechanically measure the weftyarn section between the insertion system and the winding packagesection remaining on the support. For that purpose mechanical systemsmay be employed which are controlled in adaptation to the weavingcycles.

[0015] The yarn feeding device is designed predominantly but notrestrictive for the measurement of the weft yarn length for a weavingmachine which is unable to measure the weft yarn length by itself, e.g.a jet weaving machine. In order to hardly influence the formation of theyarn winding package and the release of the yarn winding package sectionby the measurement or the definition of the correct weft yarn length foreach insertion, the engaging stop element is moved into the stopposition without using a separate drive, but by the forward moving yarnwinding package only. The stop element is brought into the engagementposition just in front of a winding just generated on the support and ina position suitable for measuring the length without interfering withthe conveying movement of the winding package. Then the stop elementdrifts with the forwardly conveyed winding package until finally thestop position is reached where the stop element defines the end of thewithdrawn weft yarn length. In order to bring the stop element lateragain into the home position, a power drive is provided which moves thestop element exclusively in the moved away release position andsubstantially opposite to the withdrawal direction while at the sametime yarn windings can be withdrawn without hindrance by the moved awaystop element. This results in a stepwise method run during which thepower drive always returns the stop element while the yarn package movesthe stop element forward. In the engaging stop position the stop elementis responsible for the termination of the insertion.

[0016] Expediently, the stop element functionally co-operates with ayarn clamp which is responsible for the start of the insertion and whichis controlled in timewise adaptation to the operation movements of thestop element. The yarn clamp holds the weft yarn firmly while thedisengaged stop element is returned to the home position. The yarn clampreleases the weft yarn first precisely at the start of the insertioncycle. The insertion then is terminated when the engaging stop elementhas reached the stop position and is caught at the stop position, beforethe yarn clamp again holds the yarn in preparation for the return motionof the stop element.

[0017] When the stop element terminates the insertion in the engagingstop position, the weft yarn may be subjected to a significantlongitudinal tension between the stop element and the insertion systemor between the stop element and even the weaving machine. Thelongitudinal tension acts backwards at least towards the stop element.The weft yarn section between the yarn clamp adjusted into the clampingposition and holding the yarn and the stop element as well will remainunder longitudinal tension. In case that then the stop element would bemoved from the engaging stop position into no longer engaging therelease position, the tension depending friction of the weft yarn at themoving stop element could disturb the tubular configuration of the yarnwinding package. Furthermore, the unavoidably occurring relaxation ofthe tensioned yarn during the movement of the stop element into therelease position also could cause a disorder of the tubularconfiguration of the yarn windings. However, by means of the auxiliarydrive the yarn clamp holding the yarn can be adjusted such that by anadjustment travel of the yarn clamp in the direction towards the stopelement still positioned in the engaging stop position the weft yarnsection extending therebetween becomes gradually relaxed and will betotally relaxed as soon as the stop element then moves into the releaseposition for the next insertion. This adjustment of the yarn clampavoids damages to the tubular configuration of the yarn winding package.Basically, it also may be expedient, to move the yarn clamp out of themoving space of the yarn at least in the final phase of an insertion,e.g. with the help of a further actuator or even with the same auxiliarydrive. This minimises the danger that the yarn might be caught by theyarn clamp. Under certain conditions it might suffice to move a shieldfor a short while over the clamping region of the yarn clamp, or toprovide a deflector at the yarn clamp or adjacent to the clamping regionof the yarn clamp which deflector then guides the yarn sidewardly pastthe clamping region, namely at the sides from which the yarn normallyenters the clamping region.

[0018] In order to move as little mass as possible during the movementof the stop element in withdrawal direction by the yarn winding package,a hinge should be provided between the stop element and the power driveof the stop element. Furthermore, the stop element ought to be guided inits moving direction in order to have precise positioning at least inthe stopping position which is important for measuring the yarn length.The guidance either may be achieved by a defined hinge axisperpendicular to the withdrawal direction and/or a guiding curve in thesupport or even in a structure adjacent to the support at the outerside, which guiding curve then may extend exactly in this direction.

[0019] A power drive on a magnetic basis is constructionally simple andfunctionally safe. A stationary solenoid pulls or pushes the at leastpartially magnetically conductive stop element in the released positionback into the home position by using the hinge. Alternatively, for thesame purpose other drives might be employed instead.

[0020] A correct positioning of the stop element in the stop positionmay be achieved by a stop provided in the guiding notch either in thesupport or in the outwardly located adjacent structure. The yarn windingpackage moves the stop element in conveying direction against the stop.

[0021] Since by an abrupt stop of the withdrawn weft yarn in the stopposition of the stop element unavoidably a whiplash effect or suddenstretching occurs in connection with a momentary yarn tension rise inthis technique, conventionally a controlled yarn brake(end-of-insertion-brake) is employed which dampens the tension rise.Such controlled yarn brakes are expensive and need a complicated controlsystem. For this reason and according to the invention in a structurallysimple way the yarn instead is dampened at the stop position of the stopelement precisely at the location where the whiplash effect or thestretching effect occurs, namely at the stop element. The dampening iscarried out by deflecting the stop element counter to a predeterminedelastic counter force essentially in circumferential direction of thesupport and by the energy which is transferred on the stop element bythe stop the weft yarn. By deflecting the stop element counter to theelastic counter force the weft yarn is decelerated gradually and energywill be dissipated to significantly alleviate or remove the weft yarntension peak. For this reason a controlled yarn brake can be omittedhere.

[0022] The above-mentioned function e.g. can be achieved by using a stopelement which itself is designed for an elastic return behaviour, e.g.with a springy hinge portion such that the stop element is deflectedlike a bending spring only under the energy increase of the whiplasheffect to alleviate the yarn tension rise. Alternatively a sidewardlypositioned retainer could be provided for the stop element in thesupport or in the structure adjacent to the support. The retainer thenis temporarily dislocated sidewardly under the force of the weft yarncounter to the predetermined counter force and together with thesidewardly moving stop element in order to dissipate energy. As soon asthe whiplash effect is over the retainer or stop element, respectively,is returned in circumferential direction into the predetermined correctlength defining stop position.

[0023] The yarn clamp which is responsible for the start of theinsertion has considerable importance since the point in time of therelease of the weft yarn has to be adapted very precisely to theoperation of the weaving machine and since only a very short time shouldexpire between the command to start the insertion and the actual releaseof the weft yarn. For that reason the yarn clamp is used as the triggerof the insertion. The yarn clamp should occupy as little space in theyarn path and should act just as close in front of the front end of thesupport that the released yarn package section can be set free for theinsertion with the desired size and without any mechanical interference.The adjustability of the yarn clamp in withdrawal direction, either in alinear or a pivoting motion, is important in order to relax the weftyarn section provided between the yarn clamp holding the yarn and thestop element positioned in the stop position after the insertion, and,under certain conditions, to move a yarn disturbing part of the yarnclamp at least substantially out of the yarn moving area. A step motoris e.g. a useful rotational drive. A solenoid assembly can be used as alinear drive.

[0024] An effective clamping at a small spot and with precisely adjustedclamping force may be achieved by a notch-like clamping region in a slimprotrusion of the yarn clamp. The clamping force is mechanicallygenerated by spring force. This can be done, because the clamping actionfor the yarn is of timewise secondary importance since then the weftyarn is caught by the stop element anyway. The spring force has toassure that the clamping force is sufficient for safely holding the weftyarn back even under tension produced by the insertion system.

[0025] Of importance is, however, that the yarn clamp releases the weftyarn precisely at the desired point in time and as rapidly as possible,when an insertion is to be introduced. This can be achieved by aswitching solenoid in a functionally simple way. The armature of theswitching solenoid is in an initial position with an intermediatepredetermined distance from a bolt tightly holding the weft yarn whilethe switching solenoid is excited. Thanks to the intermediate distancethe armature has sufficient time to overcome the static startingfriction and to convert the increasing magnetic force in high speed andto build up high kinetic energy and to accelerate strongly before thearmature hits the bolt. The switching solenoid then does not need toovercome the spring force by accelerating the armature from speed zero,but overcomes the counter force of the spring abruptly by the thenaccelerated and by the high kinetic energy of the armature. This resultsin an abrupt release of the clamped weft yarn. In practice, releasetimes in a range of only one millisecond can be achieved.

[0026] While the yarn winding package has the tendency to keep thetubular configuration for a longer time in its released section which isno longer suspended from the inner side, it may be expedient, to thensupport the yarn winding package from the outer side at least in certainregions on guiding surfaces. The suspension from the outer sidemaintains the tubular configuration and allows during withdrawal towithdraw the weft yarn from the first winding radially inwardly and thenalong the prolongation of the axis of the support such that no balloonis formed which could cause a delay and could dissipate energy, and suchthat the desired high insertion speeds or the short insertion times,respectively, are achieved.

[0027] The guiding surfaces could be formed such that they suspend atleast the lower half of the released yarn winding package section. Insome cases even a bigger part or even the entire yarn winding packagesection may be suspended. In this case the guiding surfaces could beformed by surface parts or rods or the like in order to generate as lowfriction as possible on the released yarn winding package section, or togenerate friction only there where it might be expedient, e.g. at anupper location at the front most windings in withdrawal direction inorder to prevent that those windings may inadvertently tilt forwardly.

[0028] Alternatively or additively at least a part of the guidingsurface may be inclined upwardly in withdrawal direction. Thiscontributes to maintain the released yarn winding package sectioncompact and dense while it moves forwards, and even during withdrawal ofthe yarn.

[0029] A further alternative may be to move the guiding surface togetherwith the forwardly conveyed yarn winding package in order to keepfriction influences between the guiding surface and the yarn windingpackage as low as possible. This may be achieved, e.g. by a caterpillarstructure of driven guiding surfaces which hold and convey the yarnwinding package from the outer side like spaced apart gear wheels. Atthe end of an insertion even the last yarn winding on the support may beconsumed up to the stop element in the stop position. The undesirablewhiplash effect or stretching effect could then lead to an undesirableincrease of the weft yarn tension. For that reason a holdback elementwith the shape of a lamella or a brush could be provided on top of theyarn winding package. The element co-operates with the front end of thesupport to slow down the weft yarn speed before the weft yarn comes to atotal standstill at the stop element. This element has to be adjustablesuch that it comes into action only at the respective desired point intime, namely at the end of the insertion, but does not influence thereleased yarn winding package section during the remaining time period.

[0030] In a structurally simple way the support is designed as a rodcage. The fingers of the rod cage may have individual eccentricadjustment devices with a common adjusting eccentric which is accessiblefrom the front side of the support. In this way diameter variations ofthe rod cage can be made comfortably. Since the support for carrying outthe method has a relatively small diameter, approximately correspondingto the smallest natural and unforced capability of the weft yarnmaterial to store a curvature, a simple eccentric adjustment device isenough, because a diameter variation corresponding to the length of oneyarn winding only requires a relatively small radial adjustment stroke.

[0031] Here two possibilities can be realised. The adjusting eccentriceither is rotated in the carrier and displaces the finger outwardly orinwardly, or the adjusting eccentric is rotated in the finger and isdisplaced within the carrier together with the finger and via theeccentric portion.

[0032] An outer diameter between about 20 mm and about 50 mm isexpedient for the support, preferably between about 30 mm to about 40mm. This is a diameter range corresponding to the smallest natural andunforced capability to store a curvature of most of the weft yarnmaterials processed nowadays.

[0033] Since, of course, any disturbance of the tubular configuration ofthe yarn winding package is to be avoided in order to achieve a yarnwinding package as homogenous and stable as possible, and also a stable,homogenous released yarn winding package section, it may be expedient toprovide the stop element at the lower side of the support where thegravitation force contributes towards avoiding disturbing influences ofthe stop element.

[0034] The yarn clamp should substantially be aligned in the directionof the stretched out yarn with the region at which the stop penetratesinto the support.

[0035] According to a very important aspect of the invention theoperational safety of the method can be improved significantly by aloop-suppressing body centrally provided at the support and projectingsubstantially in alignment with the support axis in withdrawal directionsuch that its free end is positioned at a location with a distance infront of the support. The basic advantages of the method are extremelyhigh insertion speeds or short insertion times, respectively. Thispositive effect results from the fact that the yarn during withdrawalout of the frontmost winding of the released winding package sectiondirectly runs substantially radially inwardly and first then in axialdirection into the weaving machine, and without any balloon formation.This yarn movement is carried out with very high speed and a highdynamic. Since the windings in the released winding package section arenot supported from the inner side but remain so to speak freely in thespace, particularly in case of lively yarn quality occasionally snarlsmay be formed which would lead to fabric faults if inserted whiletwisted or which then could cause disturbances in the insertion system,respectively. The snarl suppressing body supports the yarn run therewhere the yarn runs substantially radially inwards from the frontmostwinding and then further in axial direction. In this region thesuppressing body hinders by its structural presence that a snarl may gettwisted. Instead the untwisted snarl will be pulled open again. Thecontact occurring during the running dynamic of the yarn with thesuppressing body significantly also calms the yarn which then movesrelatively linearly in axial direction into the insertion system.

[0036] Expediently, the snarl suppressing body has a coat surface whichis rotationally symmetrical and which is tapered towards the free end.This assures that a formed snarl will slide off there and hinders thatthe snarls gets twisted. The shape also hinders that the snarl evenmight tend to wrap and tighten around the body under the withdrawaltension.

[0037] Structurally simple the snarl suppressing body is a pin,preferably a conical pin. The pin offers an ideal possibility forplacing a withdrawal sensor there for registering each withdrawnwinding.

[0038] The outer diameter of the pin should, at least close to its freeend, only amount to a fraction of the diameter of the support.

[0039] The free end should markedly project beyond the front side of thesupport in order to function also in the region in which the yarn isrunning inwardly from the released winding package section. Preferably,the free end even is located in withdrawal direction downstream of theposition of the yarn clamp in order to reach into an area downstreamwhere snarls are no longer formed and where no danger exists that asnarl could get twisted and could form a knot.

[0040] The coat surface should be smooth and should have a lowcoefficient of friction, optionally the coat surface should have a lowfriction overlay. Low friction has the meaning that the surface shouldgenerate only low friction with the yarn material. This is because thesuppressing body only by its bodily presence and extension substantiallyin withdrawal direction has to effect that snarls which are in processof being generated cannot be twisted. The body should impose as littlemechanical and delaying load as possible on the yarn.

[0041] Expediently the forward advancing movement of the winding packageis initiated by means of a predetermined conicity of the support. Thecone-conveying principle leads to the advantage of directly contactingyarn windings which then also may stick to each other in the releasedyarn winding package section. Furthermore, this is a low cost and safesolution.

[0042] Alternatively an advancing principle employing a wobbling elementin the support may be used which is driven in synchronism with thewinding the element, does not rotate but generates a wobbling motion dueto its inclined axis which wobbling motion is transferred onto the firstyarn winding exiting from the winding element and being formed on thesupport. The first yarn winding then pushes further the downstream yarnwindings.

[0043] As a further alternative the yarn winding package can be advancedaxially with so-called yarn separation generated by driven advancingelements. The advancing elements are placed between the fingers or rodsof the rod cage and use e.g. a common drive hub which has a skew axis inrelation to the axis of the support or the drive axis of the windingelement, respectively.

[0044] Basically, the yarn winding package section when presented forwithdrawal without tension and loosely, is released by overfilling thesupport. As an alternative, the support may be pulled back in relationto the yarn winding package and opposite to the withdrawal direction inorder to release the yarn winding package section at the right moment.In this case an assisting strip member may contribute to release theyarn winding package from the pulled back support in compact form and intubular configuration.

[0045] According to a further alternative an auxiliary support isassociated to the front side of the support. The auxiliary support isused to first form a yarn winding package supported from the inner side.Thereafter, the auxiliary support is coaxially pulled away from thesupport in order to release the yarn winding package section which isintended to be inserted. In this case the pull-back of the auxiliarysupport can be assisted by a stripper member which may be of advantageto keep the released yarn winding package section in compact shape.

[0046] The stretching effect or whiplash effect at the end of aninsertion into a jet weaving machine fed by weft yarns originating froma measuring feeding device is a mechanical consequence of the abruptdeceleration of the inserted weft yarn at the stop element. In order toavoid damages, in practice controlled yarn brakes are employed whichstart to brake in advance before the weft yarn is caught at the stopelement and which gradually decelerate the weft yarn. Controlled yarnbrakes of this kind need a precise electronic control system and arecomplicated and costly. According to an important aspect of theinvention the stop element itself which is responsible for the whiplasheffect or the stretching effect when reaching the stop position, is usedfor dampening or attenuating the yarn tension rise at the end of aninsertion. That is, the attenuation is carried out in the weft yarnexactly at the location where the undesirable yarn tension rise wouldcome from. For that purpose the stop element can be deflected counter toa predetermined elastic force and over a dampening stroke substantiallyin circumferential direction of the support. In more detail, the stopelement is adjusted from a first catching position in which it starts todecelerate the weft yarn over the dampening stroke into a secondcatching position and is loaded by the reaction force from the weftyarn, such that energy is dissipated before the weft yarn is totallystopped. The stop element then is returned by the predetermined elasticforce. In toto this allows a very good yarn control resulting withoutyarn breakage in a finally linearly stretched weft yarn.

[0047] For this case it may be expedient to provide at least one hingeregion between the linear drive which controls the stop element betweenthe engaged position and the released position, and the support. Thehinge region allows the sideward movability or this degree of freedom ofthe stop element without the necessity to accordingly move the lineardrive as well. The damping element movably arranged with a predeterminedmoving direction in a stationary guide can yield against spring force.The damping element is moved by the stop element by the reaction forceof the weft yarn counter to the spring force and over the dampeningstroke, such that energy is dissipated and that the yarn is brakedgradually without suffering from a significant yarn tension rise. Thedamping element does not need to move strictly in circumferentialdirection of the support, but could instead move obliquely in adirection approximately corresponding with the orientation of theresulting yarn reaction force at the stop element. The orientationresults from the substantially circumferential force of the yarnextending between the last winding at the withdrawal side and the stopelement and the substantial axial force of the downstream yarn portion.The automatic return of the damping element after the compensation ofthe yarn tension peak offers the advantage to then also pull back theweft yarn at least for a small distance.

[0048] In an alternative embodiment the yarn winding package already isformed with several yarn windings which are larger than adjacent onesand which define engagement locations for a respective one out of aplurality of stop elements. The stop elements may be formed like hooksand can e.g. be turned and move together with the yarn winding packagesuch that they sequentially may engage in the enlarged windings. Thisparticularly expedient when the yarn winding package is formed with asize which represents a weft yarn length for several subsequentinsertions.

[0049] Embodiments of the invention will be explained with the help ofthe drawings. In the drawings is:

[0050]FIG. 1 a schematic illustration of the course of a methodaccording to the invention, i.e. a method for inserting weft yarnsections into a weaving machine,

[0051]FIG. 2 a perspective schematic illustration explaining theso-called smallest unforced capability of a weft yarn material to storea curvature,

[0052]FIG. 3 a detail variant,

[0053]FIG. 4 a further detail variant,

[0054]FIG. 5 a further detail variant, prior to the start of withdrawal,

[0055]FIG. 6 the detail variant of FIG. 5 after the start of withdrawal,

[0056]FIG. 7 a perspective view of a yarn feeding device,

[0057]FIG. 8 a radial section belong to FIG. 7,

[0058]FIG. 9 a radial section similar to the radial section of FIG. 8 ofanother embodiment, in a home position of a movable stop element,

[0059]FIG. 10 a radial sectional view similar to FIG. 9 of the sameembodiment in another position of the stop element,

[0060]FIG. 11 a detail section in the plane XI-XI in FIG. 10,

[0061]FIG. 12 a schematic illustration of a further embodiment,

[0062]FIG. 13 a longitudinal section of a yarn clamp as it is used e.g.in FIG. 7,

[0063]FIG. 14 a diagram showing by means of different curves theoperation of several components in relative association during themethod,

[0064]FIG. 15 a perspective front view of a detail of FIG. 7,

[0065]FIG. 16 a detail of FIG. 15, in a perspective view and withenlarged scale,

[0066]FIG. 17 a schematic view of a method and device variant,

[0067]FIG. 18 a top view of a detail of a yarn feeding device of FIG.17,

[0068]FIG. 19 a perspective view of a further detail,

[0069]FIG. 20 a detail variant in a perspective view, and

[0070]FIG. 21 a further variant in a perspective view.

[0071] In FIG. 1 endless weft yarn material Y, e.g. coming from a notshown yarn supply, is pulled into a rotating winding element W which ismoved by a drive M with a substantially continuous rotational windingmovement R. The weft yarn material Y is wound by the winding element Won an inner mechanical support S in subsequent or adjacently placedwindings T as a tubular winding package which moves forward on thesupport S by a speed V in the direction of an arrow. The windings T thenare set free in a winding package section B beyond the end of thesupport S in withdrawal direction and further in the direction of theaxis X from the support S, while they maintain the tubularconfiguration. In the set free winding package section B the windings T1are conveyed forward loosely and substantially without tension. Due toinertia and the form stability of the winding package the windings T1remain free in the space. Approximately in alignment with the axis X aninsertion system A of a weaving machine L is provided which insertionsystem A withdraws the weft yarn Y intermittently (indicated by singlearrows C) and inserts each weft yarn Y into a weaving machine L. Betweenthe insertion system A and the winding package section B set free fromthe support S at one side and/or in the region of the end of the supportS at the other side, mechanical assemblies H and G may be provided formeasuring the respective correct weft yarn length for an insertion.Those assemblies H, G are controlled in adaptation to the weavingcycles. The weft yarn Y withdrawn from the set free winding packagesection B essentially coaxial to the axis X consumes the respectivefirst winding in withdrawal direction without any balloon formation andruns substantially radially inwards and then further axially, e.g. suchthat finally all windings T1 of the set free winding package section Bmay be consumed at the end of the insertion. Subsequently, the nextfollowing winding package section for the next following insertion isset free.

[0072] The winding package consisting of the windings T and the windingpackage section B are of round or polygonal tubular configuration. Atleast in the winding package section B the windings T1 are more or lessdensely contacting each other, are arranged in good order and havesubstantially the same form. The diameter D of the winding package isselected such that the winding curvature corresponds at leastapproximately to the smallest natural and unforced capability of theweft yarn material to store a curvature.

[0073]FIG. 2 illustrates what is meant by the smallest natural andunforced capability to store a curvature. A section E of the weft yarnmaterial Y is laid on a smooth surface 5. Both ends 3, 4 of the sectionA are moved in the direction of the arrows 1 to each other and then arereleased. The section E returns by its inherent elasticity in thedirection of the dotted arrows 2 to the shown position in which thesection has a residual curvature the radius RN of which corresponds tothe smallest natural and unforced capability of this weft yarn materialto store a curvature. This radius RN of the curvature correspondsapproximately to half of the diameter D of the winding package in FIG.1.

[0074]FIG. 3 explains schematically another variant for carrying out themethod. The inner support S on which the weft yarn winding package isformed by a substantially continuous winding process has rearwardstationary elements 6 and frontward (in withdrawal direction) locatedelements 8 which can be displaced inwardly and which e.g. are connectedvia respective hinges 7 with the elements 6. By means of a correspondingcontrol system for the movement in the direction of the dotted arrow 9the windings T1 which are pushed forward during the winding process areset free for withdrawal similar as shown in FIG. 1 by displacing theelements 8 of support S inwardly.

[0075] In FIG. 4 the support S includes e.g. cage-like provided elements10 on a carrier 11 carrying the elements 10, and, in some cases, also astationary retainer 12. By pulling back the carrier 11 in the directionof the arrow 13 a desired number of windings is set free from thesupport S for withdrawal. Alternatively, it may be possible to set freethe windings by pushing the retainer 12 forward.

[0076]FIGS. 5 and 6 show a further variant of the method. The support Sconsists of a stationary support section S1 on which the winding elementW forms the winding package with the windings T, T1 with the help of asubstantially continuous winding movement R. In withdrawal direction infront of the support section S a further, e.g. coaxial auxiliary supportS2 is provided. The auxiliary support S2 is inwardly open and includesrod-shaped elements 15 constituting a cage-like configuration connectedto a carrier 14. The elements 15 prolong the support section S1 inwithdrawal direction as long as the carrier 14 remains in the positionas shown in FIG. 5. In some cases a stationary stripper member may beprovided, although this member is not necessary in any case. As soon asby overfilling the support section S1 a predetermined number of windingsT1 is formed on the support part S2 in tubular configuration the carrier14 together with the element 15 is pulled away rapidly in the directionof the arrow 17. By this action the windings T1 are set free. From thefirst winding in withdrawal direction the weft yarn Y then runs inwardlyand in withdrawal direction through the stripper member 16 and thecarrier 14 which are formed with inner through openings.

[0077] In FIG. 6 the windings T1 already are set free. The supportsection S2 is adjusted into the right end position. By the withdrawal ofthe weft yarn Y indicated by the arrow C the set free windings T1 aresuccessively consumed back to the support section S1. After that thesupport part S2 again is returned into the position shown in FIG. 5,such that by overfilling the support section S1 again windings T1 may bebrought into the tubular configuration and can be pushed off from thesupport part S1.

[0078] With the method variants of FIGS. 3-6 also the assemblies H, Gfor measuring the weft yarn length may be used, e.g. for an insertionsystem A which is not able to measure the inserted weft yarn length byitself, e.g. in case of a jet weaving machine. The assembly H, e.g.directly co-operating with the support S, may be a controlled stopdevice with a stop element used to terminate an insertion by catchingthe weft yarn material Y, while the other assembly G may be controlledyarn clamp which initiates the start of an insertion by an openingstroke.

[0079] In all above described method variants the winding packageproduced by the winding process is pushed forwards by the windingprocess itself. Alternatively or additively even advance elements oradvance assemblies may be employed which convey the windings forward. Itis even possible to operate on the support S with a separation (pitch)between adjacent yarn windings.

[0080] For safety's sake (in FIG. 1 indicated in dotted lines) amechanical (or pneumatic) guiding surface arrangement F may be providedfor the winding package section B set free from the support S. Theguiding surface arrangement acts on the set free windings, however,exclusively from outside. The suspension by the guiding surfacearrangement F is not a must, may, however, be of advantage in order toprevent collapsing or lowering of the set free winding package sectionB. Furthermore, it is possible, to provide means which engage at the setfree winding package section B exclusively on top and from the outerside which means suppresses that the first windings T1 at the withdrawalside in the set free winding package section B may tilt forward. Thosemeans as well as the suspension by the guiding surface arrangement S donot have any influence on the balloon free consumption of the windingsT1 during the central inward withdrawal of the weft yarn Y in thedirection of the axis X of the winding package section B. The diameter De.g. may lie in a range of about 30 mm. Special yarn qualities, however,may demand a larger or even a smaller diameter D. Experience has shownthat a wide variation of yarn qualities and yarn counts have a verysimilar smallest natural and unforced capability to store a curvaturecorresponding to a radius of the curvature of about 15 mm.

[0081] The method is not only intended for jet weaving machines but mayas well e.g. be employed with gripper weaving machines, rapier weavingmachines and projectile weaving machines.

[0082]FIG. 7 illustrates a yarn feeding device 18 for carrying out themethod. Several details of the yarn feeding device 18 are shown in FIGS.8, 9, 10, 11 and 13. The yarn feeding device 18 of FIG. 7 e.g. servesfor feeding weft yarn Y into a jet weaving machine, e.g. an air jetweaving machine, the insertion system A of which is unable to measurethe weft yarn length by itself. For this reason the assemblies H, G areprovided in the yarn feeding device 18.

[0083] The driving motor M of the winding element W is received in ahousing. The winding element W rotates in relation to the stationarysupport S which is formed as a kind of a rod cage havingcircumferentially distributed, freely ending rods 19 extendingsubstantially parallel to the withdrawal direction X. The assembly H isprovided at the lower side of the support S and will be described indetail with the help of FIGS. 8-10, while the assembly G is provideddownstream of support S and is constituted by a controlled yarn clamp20.

[0084] The yarn clamp 20 is pivoted backwards and forwards by means ofan auxiliary drive 21 and about a pivot axis 21′ oriented perpendicularto the withdrawal direction X. The yarn clamp 20 comprises a tubularprojection 41 and a notch-shaped clamping region 42 for the weft yarn.The projection 41 extends from outside and perpendicular to the pivotaxis 21′ essentially below a prolongation of the support axis. A doublearrow 22 indicates how the yarn clamp 22 is adjusted back and forth bymeans of the auxiliary drive 21. The rotational auxiliary drive 21includes, e.g., a rapidly responding step motor. Alternatively, a lineardrive assembly could be provided which reciprocally displaces the yarnclamp 20 parallel to the withdrawal direction and corresponding to thedouble arrow 22. Guiding surfaces F axially overlap the support S andserve for the yarn winding package or the set free yarn winding packagesection, respectively. The guiding surfaces F, in this embodiment, arearranged at the lower side and at both sides in order to guide andsupport the set free yarn winding package section, if necessary.

[0085] Basically, it may be expedient to remove the yarn clamp 20 in theend phase of an insertion temporarily from the moving space of the yarn,e.g. by means of a separate, not shown, actuator or even by means of theauxiliary drive 21, e.g. into a position Q in FIG. 7. Alternatively, ashield could be moved for a short while above the clamping region 42. Asa further alternative, a permanent deflector could be provided there.Those measures hinder that the yarn can be caught accidentally by theyarn clamp 20 at the end of an insertion.

[0086]FIG. 8 is radial section of a variant of the yarn feeding device18. In this embodiment, the assembly H is provided below the support Sand is constituted by a stopping device having a movable stop element24. The rods 19 of the support S are provided in a stationary carrier 23in a freely cantilevering fashion. The winding element W rotates aroundthe support SW. The carrier 13, e.g. is rotatably supported on thedriving shaft of the winding element W; however, not shown solenoidarrangements hinder the carrier 23 from rotating with the driving shaftsuch that the carrier 23 remains stationary.

[0087] The stop element 24 is pin-shaped and is connected via a hinge 28having a hinge axis perpendicular to the withdrawal direction X with anarmature 25 of a solenoid drive 26 (linear drive) by which the stopelement 24 is reciprocally movable in the direction of the double arrow27 between the shown release position and an engagement position. In theengagement position the free end of the stop element 24 engages into acut-out or a longitudinal guide 13 of one rod 19. At the left end inFIG. 8 of the longitudinal guide 31 a stop 32 is provided which definesa stop position in which the engaging stop element 24 hinders that weftyarn will be further withdrawn from the windings on the support S. Thefree end of the stop element 24, e.g., is reciprocally movable in thedirection of the double arrow 21 in the hinge 28. A stop 30 defines thehome position of the stop element 24 shown in FIG. 8. In the homeposition the stop element can be brought from the shown release positionupwardly into the longitudinal guide 31 such that it will be placed infront of the yarn exiting from the winding element W and behind at leasta first yarn winding in withdrawal direction which first yarn windingalready is placed on the support S. Thanks to the hinge 28 during thefurther formation of the yarn windings the stop element 24 is carriedalong by the axially growing yarn winding package until it is caught inthe stop position at stop 32. The insertion is terminated as soon as thewithdrawn weft yarn is caught at the stop element 24. After thetermination of the insertion the stop element 24 again is pulled back bythe solenoid drive 26 into the release position such that the yarnwinding package can further overfill the support S or such that againweft yarn can be withdrawn. For returning the stop element 24 in thehome position shown FIG. 8 a power drive 33 is provided, which isstationary with respect to the stop element 24 and which may be, e.g., acontrolled solenoid 33. The solenoid 33 only is active when the stopelement 24 has to be returned. The stop element 24 only has to controlthe end of an insertion. The start of an insertion is controlled by theyarn clamp 20.

[0088]FIGS. 9 and 10 show a detail variant having a stop element 24 thehinge 28 of which is constituted by an elastic hinge section 28′ whichprovides movability in all directions. The hinge section 28′ consists,e.g., of an elastomeric part. The adjustment of the stop element 24 fromthe stop position shown in FIG. 10 back into the home position shown inFIG. 9 is carried out by the inherent elasticity of the hinge section28′, so to speak, automatically. The spring action in the spring section28′ ought to be as weak as possible in order to resist as little aspossible the yarn winding package conveying the stop element 24 forward.A permanent magnet 33 can be provided for safety's sake in order toensure in co-action with a magnetic section 35 the home position of thestop element 24 as shown in FIG. 9.

[0089] Adjacent to the support S or the rods 19, respectively, in thisembodiment a stationary structure 34 is provided distant from the spacedapart from the outer sides of the rods 19 and includes a longitudinalguide 31′ for the stop element 24. Within rod 19 or in-between two rods19 a cut-out 39 is provided as a longitudinal guide or as a passing pathfor the stop element 24. Within the structure 34 as a stop 32′ aretainer 36 is provided which defines a damping element and which willbe explained with the help of FIG. 11. The retainer 36 has to define thestop position of the stop element 24 and constitutes in co-operationwith the stop element 24 a damping device of the yarn feeding device 18.

[0090] The sectional view in FIG. 11 shows that the longitudinal guide31′ is a slot guiding the engaging stop element 24 while the yarnwinding package conveys the stop element 24 forward. In a lateral guidenotch 38 substantially oriented in circumferential direction of thesupport S or oriented in a direction which is oblique in relation to thewithdrawal direction, the retainer 36 is displaceable counter to theforce of a spring 37. The retainer 36 on the one hand forms the stop 32′for defining the stop position, and on the other hand constitutes adamping element which elastically can be displaced by the reaction forceof the decelerated weft yarn via the stop element 24 from a firstcatching position k over a damping stroke into a second catch positionI. During this stroke kinetic energy will be dissipated such that a yarntension rise at the end of an insertion is moderated or even avoided.

[0091] In a not shown alternative embodiment the stop element 24 itselfcould be displaced substantially in circumferential direction of thesupport S with a counter force and resiliently and could directlyconstitute the damping device.

[0092]FIG. 12 shows a back-holding element 39 associated to the supportS (a lamella or a brush) which extends obliquely downwards in withdrawaldirection for co-operation with the front end of the support S or theweft yarn, respectively, which weft yarn just is in progress to becaught at the stop element 24 in the stop position. The back-holdingelement 33 is adjustable, e.g., in the direction of a double arrow 40back and forth in order to act indeed only towards the end of aninsertion on the yarn to reduce the yarn speed.

[0093]FIG. 13 illustrates the structure of the controlled yarn clamp 20of FIG. 7. The tube-shape projection 41 is secured to a housing 47receiving the solenoid drive 48, 49 serving to adjust the yarn clampfrom the shown clamping position into the not shown passive position.The notch-shaped clamping region 42 is defined by a boundary surface 43of an outwardly open notch of the projection 41 and a clamping surface44 provided at a shoulder of a bolt 45 which is slideably received inthe projection 41. The bolt 45 is loaded in clamping direction by theforce of a spring 46. The spring 46, finally, serves to hold the weftyarn Y. A plunger-shaped armature 49 is provided in the solenoid drive48. The armature rests in the initial position as shown in FIG. 13 aslong as the solenoid 48 is not excited. In this initial position thearmature 49 is spaced apart from the bolt 45 by an intermediate distance50. The intermediate distance 50 allows that the armature 49 uponexcitement of the solenoid 48 accelerates rapidly and then hits withfull vehemence against the bolt 45 such that the held weft yarn Y isreleased abruptly (opening time in the range of one millisecond).

[0094] The yarn clamp 20 is adjusted from the clamping position shown inFIG. 13 into the passive position by means of a trig signal transmittedfrom the weaving machine. By this adjustment the weft yarn Y is releasedfor withdrawal in order to start the insertion cycle. On the other hand,e.g., the stop element 24 is pulled back from the engaging stop positionat the point in time after the yarn clamp 20 is brought into theclamping position by a signal generated from a not detailed showncontrol system of the yarn feeding device. In some cases even a signalof the control device of the yarn feeding device may be used to controlthe yarn clamp 20. An adjustment of the stop element 24 from the homeposition into the engagement position as well may be controlled by asignal of the control device of the yarn feeding device, e.g. as soon asthe counted number of wound on yarn windings reaches a target value. AHall sensor HS (FIG. 8) placed in the stationary part of the yarnfeeding device may e.g. serve to count the wound on yarn windings. TheHall sensor may be aligned to a permanent magnet PM provided at thewinding element W.

[0095] The method carried out with the yarn feeding device 18 will beexplained with the help of the diagram of FIG. 14 for two subsequentinsertion cycles (notch I′). The horizontal axis shows the time t or therotational angle of the weaving machine, respectively, while thevertical axis among others represents the travel strokes of theassemblies H, G in two opposite direction.

[0096] The horizontal lower parts of the notch I′ represent times duringwhich no yarn consumption takes place, while arc-shaped parts of thecurve represent respective insertions during which the predeterminedweft yarn lengths are inserted by the insertion system A into theweaving shed of the weaving machine.

[0097] The curve II indicates the substantially radial adjustment of theassembly H, i.e. of the stop element 24, between the release position aand the engagement position b. The curve III indicates the adjustment ofthe assembly G, i.e., of the clamping surface 44 relative to theboundary surface 43 of the yarn clamp 20 in longitudinal direction ofthe projection 41 between the clamping position d and the passiveposition c. The curve IV indicates the travel of the stop element 24 inthe assembly H in and counter to the withdrawal direction between thehome position f similar as shown in FIG. 8 and the stop position esimilar as shown in FIG. 10. The curve V indicates the adjustment of theassembly G, i.e. of the yarn clamp 20, in the direction of the doublearrow 22 in FIG. 7, i.e., in and counter to the withdrawal directionbetween a position g in which the yarn clamp 20 is furthest from thesupport S over an intermediate position h into a position i in which theyarn clamp 20 is closest to the support S.

[0098] According to curve II the stop element 24 in the release positionand prior to an insertion, is adjusted at a point in time t1 into theengagement position b, more precisely according to curve IV in the homeposition f close to the winding element W. Now successively new yarnwindings are formed such that according to curve IV the stop element 24conveyed by the windings gradually reaches the stop position e until thepoint in time t3. When at the point in time t1 the stop element 24 isadjusted into the engagement position b, the yarn clamp 20 still is inthe clamping position d according to curve III, such that the yarn clamp20 still holds the weft yarn. During this time period the yarn clamp 20still is in the position g with the largest distance from the support Sand according to curve V. For example, at point in time t2 a trig signalis transmitted. The yarn clamp 20 now is adjusted into the passiveposition c. The insertion starts. In the passive position the yarn clamp20 gradually is moved into the intermediate position h and according tocurve V such that the yarn clamp 20 will reach the intermediate positionh at point in time t4. At point in time t3 the insertion is to beterminated. The stop element 24 has reached the stop position e andstops, according to curve IV, such that the weft yarn is caught. Theinsertion has ended. At point in time t4 the yarn clamp 20 again isadjusted into the clamping position d according to curve III such thatthe yarn clamp 20 again holds the yarn. Thereafter the closed yarn clamp20 is moved from the intermediate position h according to curve IV intothe position i closest to the support S such that the yarn clamp relaxesthe yarn section between the stop element 24 and yarn clamp 20. Afterthe relaxation of the yarn in point in time t4 the stop element 24 ismoved into the release position according to curve II. This movement iscarried out without significant friction on the yarn and without jerkingmotions of the yarn, because the yarn already is relaxed. As soon as thestop element 24 has reached the release position, the stop element 24 isbrought by the power drive 33 according to curve IV from the stopposition e into the home position f close to the winding element W untilthe home position f is reached in point in time t1. Then the stopelement 24 again is adjusted into the engagement position b (curve II)before at point in time t2 the next insertion will start. After the stopelement 24 has been brought into the release position at point in timet5 in curve II, the yarn clamp 20 is moved according to curve V inwithdrawal direction from the position i closest to the support Sgradually into the position g in which the yarn clamp (according tocurve III) holds the yarn until the point in time t2, i.e., the start ofthe insertion.

[0099] According to curve V the yarn clamp 20 first is adjustedgradually from the position g into the intermediate position h such thatthe yarn clamp 20 reaches the intermediate position h at point in timet4. Only then the further adjustment into the position i is carried outand after the stop element 24 has been adjusted into the releaseposition.

[0100] Alternatively, the yarn clamp 20 may, different from the curve V,remain approximately in the position g between the points in time t2 andt3. The yarn clamp 20 then will be adjusted first after point in time t4in one stroke into the position i such that it reaches the position i atpoint in time t5 or shortly before.

[0101] In case of only one stop element 24 the releasable weft yarnlength only can be an integer multiple of the circumferential length ofthe support S (diameter D′). In order to adapt the weft yarn length tothe weaving width of the weaving machine the diameter D′ has to bevariable. For this purpose and according to FIGS. 15 and 16 the supportS is designed with a variable diameter. The rods 19 are, preferably ingroups, provided at fingers 51 which are radially movable in guides ofthe stationary carrier 23. The respective radial adjustment position ofthe fingers 51 is fixed by at least one fastening screw 52. Each finger51 has an individual eccenter adjustment device 53 allowing tosteplessly vary the diameter D′ of the support S. The eccenteradjustment device comprises an adjusting eccentric portion 55penetrating a cut-out 56 in the finger 51. The function of the adjustingeccentric portion 55 will be explained with reference to FIG. 16.

[0102] The eccentric portion 55 is rotatably supported about the axis 57in carrier 23 in FIG. 16, and particularly by means of a rotatableportion 58 (secured in place by a not shown safety element engaging intocircumferential groove 61). The adjusting eccentric portion 55 comprisesan eccentric portion 59 the eccentric axis of which is offset inrelation to the rotation axis 57, and a handle 60 for the engagement ofa turning tool. The eccentric portion 59 engages into the cut-out 56which extends substantially in circumferential in the finger 51,preferably in a sliding fit. By turning the adjusting eccentric portion55, e.g. over a limited rotational range of 180°, the entire adjustingrange for each finger 51 is defined. An adjustment is carried out afterfirst loosening the fastening screw 52. A new adjustment position isfixed by again tightening the fastening screw 52.

[0103] Alternatively (not shown) the adjusting eccentric portion 55 onlycould be supported rotatably in finger 51 such that it engages with itseccentric portion 59 into a cut-out in the carrier 23 which cut-out issimilar to the cut-out 56.

[0104]FIG. 17 indicates schematically how according to the method anumber of windings is formed in the yarn winding package. The number ofwindings corresponds to several weft yarn lengths. For defining thelength of each weft yarn section several stop elements 24′ are providedwhich expediently move together with the yarn winding package inwithdrawal direction and which can be brought into engagement intoselected windings T′. The windings T′ are formed larger than theadjacent windings T, e.g. with the help of a device 62 whichpreliminarily is placed close to the winding element W (double arrow 63)and which then forms one larger winding T′. A respectively selected ofthe stop elements 24′ engages into one of the enlarged windings T′ inorder to terminate the insertion of all of the windings T′ locateddownstream in withdrawal direction. Later, this stop element 24′, e.g.is returned by a turning motion into a release position, as soon as thenext insertion starts, which next insertion then will be terminated bythe subsequent engaging stop element 24′.

[0105] In FIG. 18 the stop elements 24′ are formed like hooks and areheld in rotatable bearings 65. The stop elements 24′ can be turnedbetween the engagement positions and the released positions back andforth by means of gear rims. An arrow 64 indicates the movement of thestop elements 24′ together with the forwardly conveyed yarn windingpackage in FIG. 17.

[0106] In the yarn path downstream of the yarn clamp 20 a controlledyarn brake may be provided (not shown).

[0107] In case of a weaving machine the insertion system of whichautomatically is capable of mechanically defining the weft yarn length(projectile weaving machine or rapier weaving machine) the assemblies H,G may be omitted.

[0108] During withdrawal of the yarn from the set free winding packagesection B the yarn of the frontmost winding first runs directlysubstantially radially inwards before running further substantially inaxial direction. Depending on the adhesion between the yarn windings andthe elasticity and the liveliness of the yarn material occasionallyalmost a full winding may move inwardly or the yarn may run spirallinginwardly from the frontmost winding, respectively. This could mean thatoccasionally a snarl is formed which then, in case of a lively yarnmaterial, might have the tendency to fully get twisted at the locationwhere the yarn crosses. Due to the high withdrawal speed such a snarlcould result in a knot or may not be removed but would be inserted. Thiscould cause a fabric fault or an insertion disturbance. For this reasona snarl suppressing body 70 is provided in FIG. 19 which eliminates theabove-mentioned effect. The rods 19 at the fingers 51 which are mountedin the support S at the carrier 23 about which the winding element Wrotates, e.g. in the direction of the arrow, define a support surfacehaving a certain axial length and the above-mentioned diameter D′. Thesnarl suppressing body 68, 70 is stationarily secured by a foot part 69at support S within the rods 19. The snarl suppressing body 68, 70 maybe easily removably inserted or even screwed in. The snarl suppressingbody 68, 70 extends substantially in the direction of the axis of thesupport beyond the front end of the support S, i.e. beyond the front enddefined by the rods 19, and has a free end 71. In the shown embodiment atapered rotation symmetrical pin 70 is provided the diameter of which issignificantly smaller than the diameter of the supporting surface. Atleast the free end 71 has a diameter which only is a fraction of thediameter of the supporting surface. The pin 70 may be linearly conicalor may have a concave or convex generatrice. It even may be formed likea pointed cone or as a cylinder. The coat surface 72 of the pin ought tobe smooth, in some cases it even might carry a low friction overlay inorder to generate as little friction resistance for the yarn aspossible. In the shown embodiment the snarl suppressing body 68 reacheswith its free end 71 in withdrawal direction beyond the position of theyarn clamp 20. The yarn clamp 20 is positioned in the withdrawal path ofthe yarn from the support S outside of the support axis andsubstantially aligned with the stop element 24 such that the yarnrunning off from the stop element 24 safely reaches the clamping section42. FIG. 19 also shows the guiding slot 31 for the stop element 24.

[0109] The free end 71 of the pin 70 of the snarl suppressing body 68does not need to be necessarily downstream of the yarn clamp 20. It ispossible to place the free end 71 exactly at the position of the yarnclamp 20, or even between the yarn clamp 20 and the support S. In eachcase the snarl suppressing body 68 ought to project beyond the front endof the support S in order to be able to hinder that snarls get twistedand occasionally even form knots on their way downstream.

[0110] In operation the withdrawn yarn at least sometimes may contactthe coat surface 72. In case that a snarl is in progress which has thetendency to twist about its crossing location, e.g. in case of livelyyarn material, this is hindered by the bodily presence of the snarlsuppressing body 68. A snarl cannot get twisted but will be opened andconsumed or removed. Surprisingly, a particularly positive effect of thesnarl suppressing body 68 is a very calm run behaviour of the yarn intothe insertion system.

[0111] The snarl suppressing body 68 may consist of plastic material ormetal. Instead of a pin several parallel or conically converging wiresection or the like could be employed. As mentioned, the conical pin 70could be formed with a concave or convex generatrice of its coat surface72.

[0112] Advantageously, the snarl suppressing body 68 may be used toplace a reliable yarn withdrawal sensor (FIGS. 20 and 21) for detectingthe withdrawn windings. In FIG. 20 a reflecting surface 73 (e.g. amirror) is placed on or in the coat surface 72. The surface 75 co-actswith an optoelectric sensor 74, 75. In FIG. 21 a lateral passage 76 isformed in the pin 70. A detection beam of a light emitting sensor 74′,75′ is directed through the lateral passage 76. In FIG. 20 each windingis detected once (one count) per passage, in FIG. 21 each winding isdetected twice (two counts) per passage.

1. Method for intermittently inserting weft yarns by means of aninsertion system (A) in a weaving machine (L), according to which fromendless weft yarn material (Y) at least a considerable part of the weftyarn length needed for an insertion is presented for withdrawal by theinsertion system (A) loosely and substantially without yarn tension,characterised in that a tubular yarn winding package consisting ofadjacently lying windings (T, T1) is formed on the outer side of adrum-shaped support (S) by an at least substantially continuous windingprocess, that the yarn winding package is conveyed forward substantiallyin withdrawal direction, that a number of windings (T1) of at leastsubstantially equal form substantially corresponding with the or amultiple of the weft yarn length to be inserted is set free at thewithdrawal side of the yarn winding package from the support (S) suchthat the windings (T1) maintain the tubular configuration loosely andsubstantially without yarn tension for the withdrawal, and that the weftyarn is withdrawn inwardly towards the tube axis (X) of the tubularconfiguration and further substantially along the tube axis (X) from therespective frontmost winding (T1) at the withdrawal side.
 2. Method asin claim 1, characterised in that the weft yarn is withdrawn in timewiseoverlap with the process of setting the windings free.
 3. Method as inclaim 1, characterised in that the windings (T1) are set free by axiallyoverfilling of the support (S) by the yarn winding package.
 4. Method asin claim 1, characterised in that the windings (T1) are set free overthe end of the support (S) at the withdrawal side by conveying the yarnwinding package forward on the support (S).
 5. Method as in claim 3 or4, characterised in that the yarn winding package and the set freewindings (T1) are conveyed in withdrawal direction obliquely upwards. 6.Method as in claim 1, characterised in that the windings (T1) are setfree by an adjustment movement of at least a part (S1, 8) of the support(S) relative to the yarn winding package.
 7. Method as in claim 1,characterised in that the weft yarn material (Y) is wound into thewindings (T, T1) in the yarn winding package with a curvature (D)corresponding at least approximately to the smallest natural andunforced capability of the weft yarn material (Y) to store a curvature(RN).
 8. Method as in claim 1, characterised in that the weft yarn ismechanically measured into the correct length upstream of the insertionsystem (A).
 9. Method as in claim 1, characterised in that the weft yarnlength is mechanically measured mainly by the insertion system (A). 10.Method as in claim 1, characterised in that the set free windings (T1)exclusively are supported from the outer side.
 11. Method as in claim 1,characterised in that the set free windings (T1) are supported at leastfrom the lower outer side, preferably also from the side and/or from thetop.
 12. Method as in claim 1, characterised in that the set freewindings (T1) are supported from the outer side by a suspension whichmoves approximately in synchronism with the windings conveyed forwardsin withdrawal direction.
 13. Method as in claim 1, characterised in thatthe yarn winding package is formed with several selected windings whichare enlarged in relation to adjacent windings for defining engagementwindings for mechanical length measuring assemblies (H).
 14. Yarnfeeding device (18) for a weaving machine (L), particularly a jetweaving machine, including a winding element (W) being rotatably drivenin relation to a stationary, substantially drum-shaped support (S) forforming a tubular yarn winding package consisting of adjacently lyingwindings (T, T1) of substantially equal form which yarn winding packageis conveyed forwards in withdrawal direction on the support (S), and amechanical weft yarn length measuring assembly (G, H) having at leastone stop element (24) for co-operation with the support (S), the stopelement (24) being adjustable between an engagement position (b) with anengagement from the outer side into the support (S) and a retractedrelease position (A), characterised in that the stop element (24) ismovable in withdrawal direction (X) relative to the support (S), that apower drive (33) is provided for moving the stop element (24) oppositeto the withdrawal direction (X) into a predetermined home position (F)close to the winding element (W), and that the stop element (24) in itsengagement position (b) is movable from the end position (f) inwithdrawal direction (X) to a predetermined stop position (e)exclusively by the growing yarn winding package.
 15. Yarn feeding deviceas in claim 14, characterised in that a part of the mechanical weft yarnlength measuring assembly (G, H) in the yarn path downstream of the stopelement (24) is a yarn clamp (20), which is adjustable between aclamping position (d) and a passive position (c), that the yarn clampcomprises a drive (48, 46) for adjusting the yarn clamp (20) from theclamping position (d) into the passive position (c) after an adjustmentof the stop element (24) from the release position (a) into theengagement position (b), and for adjusting the yarn clamp (20) from thepassive position (c) again into the clamping position (d) holding theyarn prior to an adjustment of the stop element (24) from the engagementposition (b) into the release position (e), and that the yarn clamp (20)releases the first firmly held weft yarn for the insertion by theadjustment from the clamping position (d) into the passive position (c).16. Yarn feeding device as in claim 15, characterised in that the yarnclamp (20) includes an auxiliary drive (21) for adjusting the yarn clamp(20) back and forth substantially in and opposite to the withdrawaldirection (X), and that the auxiliary drive (21), the drive (48, 46) ofthe yarn clamp (20) and a drive (26) of the stop element (24) co-operatesuch that the yarn clamp (20) in its clamping position (d) is movableopposite to the withdrawal direction (X) or in the direction towards thestop element (24), respectively, prior to an adjustment of the stopelement (24) from the engagement position (b) into the release position(a).
 17. Yarn feeding device as in claim 14, characterised in that ahinge (28) is provided between the stop element (24) and the drive (26)serving to adjust the stop element (24) between the engagement positionand the release position, and that the stop element (24) is movablyguided in withdrawal direction either about a hinge axis extendingperpendicular to the withdrawal direction (X) and/or in a guide (30,31′) extending in withdrawal direction (X), the guide (30, 31′) beingprovided either in the support (S) or in a structure (34) locatedadjacent to the support (S).
 18. Yarn feeding device as in claim 14,characterised in that the power drive (33) includes a controlledsolenoid (33′) which is stationarily provided in relation to the stopelement (24) and which, when activated, produces a force at a portion(33) of the stop element (24) in a direction opposite to the withdrawaldirection (X).
 19. Yarn feeding device as in claim 14, characterised inthat the support (S) or a stationary structure (34) located adjacent tothe support (S) has a stop (32, 32′) for defining the stop position (e)of the stop element (24).
 20. Yarn feeding device as in claim 14,characterised in that the stop element (24) in the stop position (e) isdeflectable in circumferential direction of the support (S) with apredetermined resilient counter force.
 21. Yarn feeding device as inclaim 20, characterised in that the stop element (24) itself is formedsuch that it is deflectable in circumferential direction of the supportagainst a predetermined counter force and is resiliently returnable,preferably by means of a springy section (28′) of the hinge (28). 22.Yarn feeding device as in claim 20, characterised in that a sidewardlypositioned retainer (36) is provided in the support (S) or in thestationary structure (34) located adjacent to the support (S), theretainer (36) forming the stop (32′) for defining the stop position (e),and that the retainer (36) is displaceable in circumferential directionof the support by the stop element (24) and against the predeterminedresilient counter force (37), and that the retainer (36) automaticallyreturns under the force (37).
 23. Yarn feeding device as in claim 15,characterised in that the yarn clamp (20) is provided with a tubularsmall diameter projection (41) including a notch-shaped yarn clampingregion (42), that the projection (41) is placed close to the front endof the support (S), that the projection (41) extends freely ending froma support location outside of the axial projection of the outer diameter(D) of the yarn winding package essentially crosswise to the withdrawaldirection (S) through the yarn withdrawal path and that the auxiliarydrive (21) of the yarn clamp (20) is arranged in the support location,the auxiliary drive (21) being constituted by a rotational drive havinga rotation axis (21′) substantially perpendicular to the withdrawaldirection and to the longitudinal axis of the projection (41) or alinear displacement drive for a displacement direction essentiallyparallel to the withdrawal direction.
 24. Yarn feeding device as inclaim 23, characterised in that the notch-shaped clamping section (42)is defined by a boundary surface (43) of an outwardly open notch formedin the projection (41) and by a clamping surface (44) of a bolt (45)longitudinally displaceable received in the projection (41), and thatthe bolt (45) in the clamping position (d) of the yarn clamp (20) isloaded by spring force (46) and is pressed with its clamping surface(44) with the weft yarn (Y) held in-between against the boundary surface(43).
 25. Yarn feeding device as in claim 15, characterised in that adrive of the yarn clamp (20) includes a switching magnet (48) inclusivea plunger-shaped armature (49), that the armature (49) engages at thebolt (45) opposite to the spring force (46) when current is supplied tothe switching magnet, and that in the clamping position (d) of the yarnclamp (20) a predetermined intermediate distance (50) is formed betweenthe armature (49) and the bolt (45), while no current is supplied to theswitching magnet and while armature (49) maintains a predeterminedinitial position.
 26. Yarn feeding device as in claim 14, characterisedin that at least one outer guiding surface (F) for the yarn windingpackage section (B) set free during overfilling the support (S) isarranged in withdrawal direction (X) following the support (S), that theguiding surface (F) extends substantially in withdrawal direction, andthat, preferably, the guiding surface (F) extends in withdrawaldirection beyond the yarn clamp (20) and overlaps the front end of thesupport (S).
 27. Yarn feeding device as in claim 26, characterised inthat the guiding surface (F) at least grips from the outer side aroundthe lower half of the yarn winding package, preferably grips around morethan the lower half to, preferably, even around the entire yarn windingpackage.
 28. Yarn feeding device as in claim 26, characterised in thatthe guiding surface (F) consists in circumferential direction of theyarn winding package of single partial surfaces or finger-shaped orrod-shaped elements.
 29. Yarn feeding device as in claim 26,characterised in that at least a part of the guiding surface (F) belowthe set free yarn winding package section (B) is inclined obliquelyupwardly in withdrawal direction.
 30. Yarn feeding device as in claim26, characterised in that a drive for moving the guiding surface (F)substantially in withdrawal direction together with the yarn windingpackage is provided, at least for moving a part of the guiding surface(F).
 31. Yarn feeding device as in claim 14, characterised in that aback holding element (39) is provided over the top of the yarn windingpackage, that the back holding element (39), preferably, is a lamella, abrush or a lateral arm, that the back holding element (39), preferably,is movable from a raised neutral position to a lowered holding position,and that the back holding element (39) in the holding position is incontact with the weft yarn material and/or the support with the backholding element (39) extending obliquely downward from the top over theend of the yarn winding package at the withdrawal side while the end ofthe yarn winding package remains supported by the support (S).
 32. Yarnfeeding device as in claim 14, characterised in that the support (S) isformed as a diameter variable rod cage having rods (19) extendingsubstantially parallel to the withdrawal direction (X), that the outerperipheries of the rods (19) form a support surface for the yarn windingpackage, that the rods (19), preferably in rod groups, are provided onfingers (51) which are adjustably guided substantially radially withrespect to the axis of the support in a stationary carrier (23) andwhich can be fixed in different radial adjustment positions, and thateach finger (51) is equipped with an individual eccenter adjustmentdevice (53) including an adjusting eccentric portion (55) accessiblefrom the front side of the support (S).
 33. Yarn feeding device as inclaim 32, characterised in that the adjusting eccentric portion (55) issupported in the carrier (23) for rotation about an axis parallel to theaxis of the support (S), preferably for an adjustment over a limitedrotational range of 180°, and that the adjusting eccentric portion (55)engages by an eccentric portion (59) into a cut-out (56) of the finger(51) which cut-out is oriented in circumferential direction.
 34. Yarnfeeding device as in claim 32, characterised in that the adjustingeccentric portion (55) is supported in the finger (51) for rotationabout an axis parallel to the axis of the support, preferably over alimited rotational range of e.g. 180°, and that the adjusting eccentricportion (55) engages with an eccentric section into a cut-out in thecarrier (23) which cut-out is oriented in circumferential direction. 35.Yarn feeding device as in claim 14, characterised in that the support(S) has an outer diameter (D′) between about 20 mm and 50 mm, preferablybetween about 30 mm and 40 mm.
 36. Yarn feeding device as in claim 14,characterised in that the stop element (24) is located at the lower sideof the support (S).
 37. Yarn feeding device as in claim 23 or 36,characterised in that the clamping section (42) of the yarn clamp (20)is positioned at the outer side of the axis of the support (S) and inwithdrawal direction of the weft yarn (Y) substantially in alignmentwith the stop element (24).
 38. Yarn feeding device as in claim 14,characterised in that a snarl suppressing body (68) is centrallyprovided at the support (S), preferably in removable fashion, that thesnarl suppressing body (68) extends from the support (S) at leastapproximately in alignment with the axis of the support in withdrawaldirection, and that the snarl suppressing body (68) has a free end (71)located at a position in distance ahead of the front of the support (S).39. Yarn feeding device as in claim 38, characterised in that the snarlsuppressing body (68) has a rotation symmetrical coat surface (72)tapering in the direction towards the free end (71) and that,preferably, a yarn withdrawal sensor (73, 74, 75, 74′, 75′, 76′) isstructurally associated to the snarl suppressing body (68). 40 Yarnfeeding device as in claim 38, characterised in that the snarlsuppressing body (68) is a pin (70), preferably a conical pin.
 41. Yarnfeeding device as in claim 40, characterised in that the outer diameterof the pin (70), at least close to the free end (71), amounts to afraction of the diameter (D′) of the support (S) only.
 42. Yarn feedingdevice as in claim 38, characterised in that the free end (71) islocated close to the position of the yarn clamp (20), preferably inwithdrawal direction downstream of the position of the yarn clamp (20).43. Yarn feeding device as in claim 39, characterised in that the coatsurface (72) is smooth and formed with low friction, preferably byproviding a low friction overlay.
 44. Yarn feeding device as in claim14, characterised in that the surface of the support (S) is formed witha conicity tapering in withdrawal direction (X), preferably with aninclination of about 1°.
 45. Yarn feeding device as in claim 14,characterised in that an advance element is provided between the windingelements (W) and the surface of the support (S), and that the advanceelement is driven in synchronism with the winding element (W) for awobbling motion.
 46. Yarn feeding device as in claim 14, characterisedin that advance elements are provided between the rods (19) of the rodcage of the support (S), that the advance elements are connected to acommon drive driving the advance elements in synchronism with thewinding element (W) in withdrawal direction back and forth inoscillating fashion such that each advance element during the forwardmotion protrudes relative to the adjacent rods (19) and beyond the rodsoutwardly and returns during the backward motion relative to theadjacent rods (19) again inwardly and behind the rods (19).
 47. Yarnfeeding device as in claim 14, characterised in that the support (S) isarranged such that it can be pulled back relative to the yarn windingpackage and opposite to the withdrawal direction (X) to set the yarnwinding package section free.
 48. Yarn feeding device as in claim 47,characterised in that a substantially stationary strip-off member (12)is provided, and that the support (S) is arranged such that it can bepulled back relative to the strip off member (12)
 49. Yarn feedingdevice as in claim 14, characterised in that a coaxial ring-shapedauxiliary support (S2) is structurally associated to the front end ofthe support (S, S1), that the auxiliary support (S2) has at least aboutthe same outer diameter (D′) as the support (S, S1), that the auxiliarysupport (S2) is arranged such that it can be adjusted between a yarnwinding position at the front end for prolonging the support (S, S1)into a gap position axially out of the yarn winding package, such thatit forms an intermediate distance with the front end in the gap positionfor withdrawing the weft yarn through the auxiliary support (S2). 50.Yarn feeding device as in claim 49, characterised in that the auxiliarysupport (S2) is arranged such that it can be shifted into the gapposition relative to a substantially stationary, ring-shaped strip offmember (16).
 51. Yarn feeding device as in claim 14, characterised inthat a cyclically drivable device (62) is arranged between the windingelements (W) and the support (S) for selectively forming single enlargedwindings (T′), that several hook-shaped stop elements (24′) are arrangedsuch that they can be moved together with the yarn winding package andthat they can be moved, preferably, turned in and outwardly, and thateach stop element is movable into an engagement position in which itengages into one of the larger windings (T′) which are formed in theyarn winding package among other smaller adjacent windings.
 52. Yarnfeeding device for weaving machines, particularly for a jet weavingmachine, comprising a winding element (W) arranged for driven rotationrelative to a stationary support, a stop element (24) for measuring theweft yarn length, the stop element (24) being movable back and forthsubstantially radially to the axis of the support (S) and in relation tothe support (S) between a retracted yarn release position (a) and anengagement position (b) for catching the weft yarn in the engagementposition, which weft yarn is withdrawn by the weaving machine out ofwindings (T, T1) of a yarn winding package formed on the support (S),characterised in that the stop element (24) is arranged in theengagement position (b) such that it is deflected by the weft yarn (Y)out of a first catching position (k) counter to a predeterminedresilient force and over a damping stroke in circumferential directionof the support (S) into a second catching position (I).
 53. Yarn feedingdevice as in claim 52, characterised in that the stop element (24) isconnected with a linear drive (25, 26) for adjusting the stop element(24) between the engagement position (b) and the release position (a),that the stop element (24) includes a hinge section (28, 28′) betweenthe support (S) and the linear drive, and that an automaticallyreturning damping element (36) is provided in a stationary guide (38)oriented in circumferential direction, the damping element (36) beingdisplaceable counter to spring force (37) by the stop element (24).